An attempt will be made to identify the active transport of an ion responsible for the pump in the corneal endothelium by simultaneously measuring the flux of water and two ions, as well as the electrical potential across the layer. Endothelial layers will be grown in tissue culture and it will be seen if it can be induced to show active pumping in this state. These layers will be tested as donor endothelial grafts. Attempts will be made to prolong the life of the cells by supplying them with substrates, particularly those required for lipid synthesis. Electron microscopy will be used to search for morphological evidence of fluid transport, particularly by plasma membrane bounded volumes such as intracellular vesicles or the intercellular spaces. Evidence for intercellular movement will be pursued by tracer studies and by microscopy of the fluid layer bounding the surface of the cell layer. A biomicroscope constructed on an original principle will be used to examine the architecture of the corneal stroma in the normal and swollen states and to identify the structures responsble for light scattering. It will also be used to examine the morphology of the endothelial cells and other transparent ocular structures. A study of the mechanism of excitation of corneal nerves will be initiated. Whether temperrature and touch are mediated through the same nerve endings will be re-examined in an isolated corneal preparation. The nerve-excitation mechanism will be studied by searching for synergistic action between stimuli. An attempt to find whether the nerves are stimulated by a neurotransmitter released from the epithelial cells will be made by using microstimuli which can be limited to a small area of the cell.